Anti-theft device for motor vehicle fuel tank

ABSTRACT

An anti-siphoning device for vehicle fuel tanks includes a barrier in the form of a honeycomb with hexagonal openings located between the fuel tank inlet and the tank itself. The device includes a retractable extension to accommodate a fuel refilling nozzle and openings to allow air in and out of the tank, which makes the refilling process easier.

FIELD OF THE INVENTION

This invention relates to an anti-siphoning device for a motor vehiclefuel tanks.

BACKGROUND OF THE INVENTION

The Applicant is aware of a device which is fitted to the fuel tankopening which prevents insertion of a siphon to empty the tank. Howeverthe device has the undesirable side effect of substantially increasingthe time required to refuel each tank. As each truck usually hasmultiple tanks, this results in an unacceptable time cost to theoperator.

It is therefore an object of this invention to provide an anti-siphoningdevice which prevents loss of fuel without compromising the time takento refuel the tanks. It is a further object of this invention to providean anti-siphoning device which is universal and capable of fitment to awide variety of vehicle fuel tanks.

THE INVENTION

According to the invention, an anti-siphoning device for motor vehiclefuel tanks comprises a cylindrical housing securable within the fueltank inlet; anchoring means for securing the housing within the inlet, abuffer to prevent insertion of a siphon tube element and an extensibleneck element movable from a first position in which insertion of a fuelpump nozzle is prevented, to a second position in which the device hassufficient depth to receive the fuel pump nozzle for the purposes offilling the tank, the housing defining a passage between the tank inletand the housing for free flow of air into and out of the tank duringfilling, the passage being in communication with the atmosphere by meansof one or more air vents located in the housing.

In the preferred form of the invention, the buffer element andextensible neck element comprise a pair of concentric cylindricalelements locatable within the cylindrical housing, the buffer elementcomprising the innermost cylinder and including at the upper end thereofa grid affixed thereto and the neck element being slidable between thehousing and the buffer element. The housing preferably includes a pairof vertical slots including at the upper ends thereof a horizontal slot,in which guide formations on the perimeter of the neck element areslidable. These permit vertical movement of the neck element as well asproviding a means to retain the neck element in the extended positionduring filling.

The housing preferably includes a circumferential flange at the top endthereof with the air vent being located spaced apart around the collar.

The bottom end of the cylindrical housing includes one or moreformations for retaining the buffer and neck elements and preventingthem from slipping into the tank. In the simplest form, the formationcomprises an inwardly directed circumferential flange providing ledge onwhich the bases of the neck and buffer elements rest. In a preferredform, a second grid is provided which also acts as a further barrier toinsertion of narrow-diameter siphon-tube. In the preferred form, thegrid pattern comprises a plurality of half-hexagonal apertures.

The neck element includes at the upper end thereof a collar about theopening thereof to engage the inner diameter of the housing, the collarbeing provided with a pull-ring or the like formation for lifting itinto the extended position required for filling.

In the preferred form of the invention, the upper grid is circular inshape and comprises a plurality of hexagonal apertures within theperimeter of the circle. Save for the apertures at the perimeter of thegrid, all apertures are hexagonal as the Applicant has established thatthis shape permits the lowest interstitial surface area whichaccordingly reduces resistance to flow of the fuel therethrough andthereby reduces splash back and frothing. This reduction of surface areacan also be achieved with square apertures.

In the preferred form of the invention, the cylindrical housing issecurable within the tank inlet by means of a mounting plate whichcomprises a ring element including two or three spaced-apart lugs eachadapted to receive a bolt, depending on the make of truck to which it isto be fitted. The flanges engage cutout formations in the filler neckand the filler neck may have either two or three cut outs. When thedevice of the invention is fitted, the lugs are inserted into thecutouts and the ring element is rotated until the lugs abut againststopper elements at which point the bolts in the lugs are tightened andfurther bolts are inserted to prevent reverse rotation of the ringelement.

The circumferential flange of the cylindrical housing engages by meansof feet located on the underside of the flange and the bolts extendthrough the circumferential flange of the cylindrical housing. In thisform of the invention, the position of the housing and neck and bufferelements is adjustable by tightening or loosening the bolts to draw themcloser to the top of the tank inlet or urge them further away,respectively. This enables the device of the invention to fit better ina wider range of fuel tanks as these tanks have filler necks at the tankinlets which vary widely in size in different vehicles. In addition thedimensions of the feet may differ to facilitate fitment in differentvehicles.

In operation, when the fuel tank of a vehicle is required to be filled,the neck element is pulled upwards using the pull-ring and rotated tokeep it in the extended position. When in the first position describedin earlier paragraphs, the device of the invention prevents insertion ofnot only a siphoning device but also a fuel-pump nozzle because of theproximity of the honeycomb grid to the top of the tank inlet. In theextended position, the neck element provides sufficient depth forinsertion of the nozzle.

Fuel flows virtually unobstructed through the honeycomb grid into thetank while displaced air from the tank flows upwards around thecylindrical housing of the device, and out through the air-vents locatedaround the flange. The efficiency of the honeycomb grid as an inlet tothe fuel together with the separation of the flow passages of fuel inand air out reduce splash back and frothing of the fuel, substantiallydecreasing filling times associated with prior art anti-siphoning deviceof a similar nature.

In an alternative form of the invention, the housing is not mounted on aring mounting plate, but is instead provided with a series ofspaced-apart spring clips which are biased to engage the underside ofthe circlip to prevent removal. This form of the invention is typicallyused for inlet tanks which include a circular groove within the inlet.In this form of the invention, the mounting plate is replaced by acirclip ring which fits underneath the circumferential flange of thecylindrical housing and engages the circular groove in the inlet and inso doing ensures a firm mounting for the anti-siphoning device of theinvention.

EMBODIMENT OF THE INVENTION

Embodiments of the invention are described below with reference to theaccompanying drawings in which:

FIG. 1A is an isometric view of an anti-siphoning device of theinvention;

FIG. 1B is an isometric view of an anti-siphoning device of theinvention mounted with a fuel tank inlet;

FIG. 1C is an isometric view of an anti-siphoning device adapted toreceive a screw-threaded cap;

FIG. 2 is a similar view of the device of FIG. 1B with the neck elementin extended condition for fueling;

FIGS. 3 and 4 are bottom isometric views of FIGS. 1B and 2 respectively;

FIGS. 5 and 6 are cutaway views of FIGS. 1B and 2;

FIGS. 7 and 8 are cutaway views of FIGS. 3 and 4;

FIG. 9 is an isometric view of one form of a ring mounting element;

FIG. 10 is an isometric view of an alternative form of the invention;

FIG. 11 is a cutaway isometric bottom view of FIG. 1C; and

FIG. 12 is an alternative cutaway view of the device of FIG. 1C.

In FIGS. 1 to 12, an anti-siphoning device 10 to prevent fuel beingsiphoned from motor vehicle tanks, fits within the inlet of the tank.

The truck tank inlet includes an integral filler neck which may differin dimensions from vehicle to vehicle.

The device of the invention comprises includes an adaptor 12 which fitsonto the truck filler neck and cylindrical housing 14 which includes atthe top end thereof a circumferential flange 16. Within the housing is aconcentric arrangement with an extensible neck element 18 and bufferelement 20 which has a honeycomb grid 22 at the top end thereof toprevent insertion of a pipe or tube for siphoning purposes.

The neck element 18 includes a collar 24 for engaging the internal edgeof the flange 16 when in the position of FIG. 1 in which no filling ofthe tank is taking place. A pull-ring 26 is provided to assist insliding the neck element from the position of FIG. 1 to the extendedposition of FIG. 2 to fill the tank. The external surface of the neckelement is provided with a guide formation 28 which slides in slot 30cut in the cylindrical housing 14. The slot includes a horizontalsection 32 at the top end thereof which enables the neck element to berotated to the end of slot 32 (as shown in FIG. 2) to be retained in theextended position during filling.

At the bottom end of the housing 14, a second grid 34 is provided andsecures the bases of the housing (14) and buffer (20) elements to thegrid 34 by means of welds at 40. This renders the housing 14 and bufferelement 20 fixed while the neck element 18 is free to slide. The grid 34has a half-honeycomb grid pattern 35. The lower end of the housingfurther includes horizontally orientated slots 37 to assist free flow offuel and reduce splash back.

The housing 14 is secured in the inlet by means of bolts 42 which extendthrough the flange 16 to engage lugs 44 on mounting ring 46 as shown inFIG. 3.

During fitment, the mounting ring is inserted into the truck filler neckwith the lugs 44 entering cutouts 47 in the adaptor 12. The ring is thenrotated until the lugs abut stopper elements 49. Once the neck andbuffer elements have been slided into the housing, the bolts 42 aretightened to draw the ring upwards to engage the underside of the fillerneck of the vehicle. Feet 50 are provided on the underside of the flange16 to centralize the anti-siphoning device 10. Locking screws 43 preventforced removal of the device. The bolts 42 permit adjustment of thedistance between the flange 16 and the mounting ring 46, to allowfitment in a variety of fuel tanks having filler necks of differentdimensions.

When the neck 18 is in extended position required for filling as shownin FIGS. 2, 4, 6 and 8, there is sufficient depth for insertion of afuel-pump nozzle into the neck. Fuel is pumped through the honeycombgrid 22 into the tank, and air displaced by the fuel flow upwards aroundthe outside of the housing 14 and out through vents 48 in flange 16.

This arrangement ensures that flow of air and fuel remains discrete fromeach other and accordingly prevents frothing from reducing the speed offuel that can enter the tank.

Turning to FIG. 10, an alternative form of anti-siphoning device isshown. The method and principle of operation remains identical, but themethod of mounting the device within the tank inlet differs. In thisform, a circlip 52 is provided which engages a circular groove in thetank inlet on one hand, and the underside of flange 16 on the other.Spring clips 54 also engage the underside of the circlip 52 to preventremoval.

In FIGS. 1C and 11, and 12 the truck filler neck is screw-threaded toreceive a cap (not shown). In this form, securing of the housing in thetank inlet is achieved by the flange 16 resting on the tank inlet andinternally screw-threaded 56 adaptor 12 being secured to the truck tankinlet by means of dowel pins 60 which engage the screw-thread of thetank inlet and prevent removal. The flange 16 is held between theadaptor 12 and the inlet by means of lip 62 which is shaped for thispurpose.

1. An anti-siphoning device for motor vehicle fuel tanks comprising acylindrical housing securable within the fuel tank inlet; anchoringmeans for securing the housing within the inlet, a buffer to preventinsertion of a siphon tube element and an extensible neck elementmovable from a first position in which insertion of a fuel pump nozzleis prevented, to a second position in which the device has sufficientdepth to receive the fuel pump nozzle for the purposes of filling thetank, the housing defining a passage between the tank inlet and thehousing for free flow of air into and out of the tank during filling,the passage being in communication with the atmosphere by means of oneor more air vents located in the housing.
 2. An anti-siphoning devicefor motor vehicle fuel tanks as claimed in claim 1 in which the bufferelement and extensible neck element comprise a pair of concentriccylindrical elements locatable within the cylindrical housing.
 3. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the buffer element comprises the innermost cylinder andincludes at the upper end thereof a grid affixed thereto.
 4. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which and the neck element is slidable between the housing and thebuffer element.
 5. An anti-siphoning device for motor vehicle fuel tanksas claimed in any of claim 1 in which the housing includes a pair ofvertical slots including at the upper ends thereof a horizontal slot, inwhich guide formations on the perimeter of the neck element areslidable.
 6. An anti-siphoning device for motor vehicle fuel tanks asclaimed in claim 5 in which the guide formations permit verticalmovement of the neck element as well as providing a means to retain theneck element in the extended position during filling.
 7. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the housing includes a circumferential flange at the top endthereof with the air vents being located spaced apart around the collar.8. An anti-siphoning device for motor vehicle fuel tanks as claimed inclaim 1 in which the bottom end of the cylindrical housing includes oneor more formations for retaining the buffer and neck elements andpreventing them from slipping into the tank.
 9. An anti-siphoning devicefor motor vehicle fuel tanks as claimed in claim 8 in which theformation comprises an inwardly directed circumferential flangeproviding a ledge on which the bases of the neck and buffer elementsrest.
 10. An anti-siphoning device for motor vehicle fuel tanks asclaimed in claim 8 in which the formation comprise welds.
 11. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the neck element includes at the upper end thereof a collarabout the opening thereof to engage the inner diameter of the housing,the collar being provided with a pull-ring or the like formation forlifting it into the extended position required for filling.
 12. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 3in which the grid is circular in shape and comprises a plurality ofhexagonal apertures within the perimeter of the circle.
 13. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the grid is circular in shape and comprises a plurality ofsquare apertures within the perimeter of the circle.
 14. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the cylindrical housing is securable within the tank inlet bymeans of a mounting plate which comprises a ring element including twoor three spaced-apart lugs each adapted to receive a bolt
 15. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which an adaptor is provided to secure the housing in the tank inlet.16. An anti-siphoning device for motor vehicle fuel tanks according toclaim 15 in which flanges engage cutout formations in the adaptor andthe adaptor has either two or three cut outs.
 17. An anti-siphoningdevice for motor vehicle fuel tanks as claimed in claim 16 in which,when the device is fitted, lugs are inserted into the cutouts in theadaptor and the ring element is rotated until the tugs abut againststopper elements at which point the bolts in the lugs are tightened andfurther bolts are inserted to prevent reverse rotation of the ringelement.
 18. An anti-siphoning device for motor vehicle fuel tanks asclaimed in claim 7 in which the circumferential flange of thecylindrical housing engages by means of feet located on the underside ofthe flange and bolts extend through the circumferential flange of thecylindrical housing.
 19. An anti-siphoning device for motor vehicle fueltanks as claimed in claim 18 in which the position of the housing andneck and buffer elements is adjustable by tightening or loosening thebolts to draw them closer to the top of the tank inlet or urge themfurther away, respectively.
 20. An anti-siphoning device for motorvehicle fuel tanks as claimed in claim 18 in which the dimensions of thefeet differ to facilitate fitment in different vehicles.
 21. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim 1in which the housing is provided with a series of spaced-apart springclips, and the mounting plate is replaced by a circlip ring which fitsunderneath the circumferential flange of the cylindrical housing andengages the circular groove in the inlet, the spring clips being biasedto engage the underside of the circlip to prevent removal.
 22. Ananti-siphoning device for motor vehicle fuel tanks as claimed in claim15 in which the adaptor is internally screw-threaded to engage thecorrespondingly screw-threaded tank inlet/filler neck, thecircumferential flange being held between the tank inlet and a lipformation in the underside of the adaptor.
 23. An anti-siphoning devicefor motor vehicle fuel tanks as claimed in claim 22 in which the adaptoris secured with dowel pins which prevent the adaptor being unscrewed.24. (canceled)